Changing material values and A-values

[Browne Dan]

Dear Thomas,

Thanks for all the earlier help. A few more things please. Please see below the typical values for the brick, ‘Stewartby Fletton’, that I’m simulating. This is all I have supplied to me by the manufacturer.

Gross Density = c.1390 kg m-3
Net Density = c.1740 kg m-3
Frog Volume = c.17%
Initial Rate Of Water Absorption = c.1.5-2.0 kg m-2 min-1
24 Hour Cold Water Absorption = c.16-17%
5 Hour Boil Water Absorption = c.19-20%
Saturation Coefficient = 0.85
Apparent Porosity = c.33-34%
Compressive Strength = c.32-38 N mm-2
Thermal Conductivity = c.0.47 W m-1 K-1
Specific Heat Capacity = c.1 kJ kg-1 K-1

Notes: Water absorptions quoted on weight / weight basis
Saturation coefficient = Cold water absorption / Boil absorption
Apparent porosity = Boil absorption quoted on volume / volume basis
Compressive strength is quoted for brick laid frog up (frog filled with mortar)
Thermal conductivity tabulated value from EN 1745:2002 based on brick density

I have interpreted this to mean the following:

Density = 1390 kg/m3
Porosity = 0.278 m3/m3
H.Cap = 1000 J/kgK
Dif.Res.Fac = 16 (this is a guess and I will change it to see how much influence it has on my results)
Free water saturation = 0.236 kg/m3

As discussed this gives a very steep sorption curve (I was hoping to include screenshots but i cant work out how to insert them into this post?)


Q1. Firstly have I interpreted the values correctly?

Q2. I’m not sure about which density to use, is WUFI capable of considering the percentage of mortar in the simulation? If not then should I take the ‘net density’ as the ‘bulk density’ value?

Q3. A-value. We established earlier that the A-value from the above values is 0.26. When I look in 'hygric extensions' at the 'liquid transport coefficient', 'suction' and 'redistribution', I see two columns 'water content' and 'DWS'. When i click 'generate' i have the option to add 0.26 to the box named 'water absorption coefficient' which has in brackets after it[kg/m2s ^0.5]. If I then click OK then an error message comes up asking for a 'reference water content' and I'm not sure what value to give it.

I hope this makes sense and I look forward to hearing from you as soon as possible
Kind regards

Dan